Synthesis of the glomerular basement membrane in the rat kidney. Autoradiographic studies with the light and electron microscope

Effects of mesangial localization of polyvinyl alcohols on glomerular basement membrane thickness

We studied the effects of mesangial localization of polyvinyl alcohols (PVA) on glomerular basement membrane (GBM) thickness in inbred Lewis rats. To avoid possible influences of PVA redistribution after localization in liver, lung, and other organs, the kidneys of rats given PVA were transplanted into uninephrectomized normal rats. Normal kidneys transplanted into normal rats served as a control. GBM thickness at the time of transplantation was the same in PVA kidneys as in normal kidneys. However, by 18 weeks post-transplant GBM thickness was greater in PVA kidneys, and this increase was sustained at 30 weeks. Within the glomeruli of PVA kidneys, lobules with marked mesangial PVA accumulation had more marked GBM thickening than lobules with little or no PVA accumulation. It is concluded that changes within the mesangium can influence GBM thickness. Whether this represents a direct effect of mesangial architectural distortion, a consequence of local phlogistic activities such as the influx of macrophages into the mesangium of glomeruli with PVA localization, or the result of intraglomerular hemodynamic perturbations is unclear.

Induction of dipeptidylpeptidase IV activity in human renal glomeruli--a histochemical study

An enzyme histochemical study of various lysosomal storage diseases, primary renal diseases, but also of cases with no detectable renal pathology, revealed a prominent induction of dipeptidylpeptidase IV (DPP IV) activity in human renal glomeruli from practically zero values seen under normal circumstances. The common denominator responsible for enzyme activity induction it not clear. Podocytes were seen as the main cell type bearing the enzyme activity. Aminopeptidase M exhibited no such phenomenon of induction.

Testosterone-dependent changes in vivo and in vitro in the structure of the renal glomeruli of the teleost Gasterosteus aculeatus L

During the reproductive period of the male stickleback, structural and functional changes of the kidney take place, both in the glomeruli and in the renal tubule cells. The structural changes in the glomeruli involve almost all glomerular components and point to a reduction of the glomerular filtration rate. The purpose of this study was to investigate whether these changes are controlled by testosterone, indirectly or directly. In vivo experiments demonstrated that exposures of immature castrates for 8 days to methyltestosterone leads to activation of mesangial cells and podocytes, to slight expansion of mesangial matrix and slight thickening of basal lamina. Observations on cultured renal tissue showed that two androgens, 11-ketotestosterone and methyltestosterone, are also able to stimulate the secretory activity of podocytes and mesangial cells in vitro. The results therefore indicate, that most glomerular changes in male sticklebacks during the reproductive season are directly effected by testosterone.

Morphometry of the renal corpuscle during postnatal growth and compensatory hypertrophy

Morphometry was used to measure the growth changes in renal corpuscle and glomerular size and composition in outer, middle, and inner cortical layers during postnatal development in normal and mononephrectomized rats. Glomerular growth was 4.16-fold in normal rats and 6.12-fold after nephrectomy. The cell populations in glomeruli showed distinctly different growth patterns. Cellular hypertrophy and hyperplasia during normal growth were 2.72 and 1.52 for epithelial cells, 0.93 and 3.70 for endothelial cells, and 1.28 and 2.65 for mesangial cells; corresponding values during stimulated growth were 2.75 and 1.92, 1.19 and 4.11, and 1.65 and 3.09. A linear transcortical gradient of corpuscle diameters was found in young animals and normal adults, with the mean volume of juxtamedullary renal corpuscles two times greater than that of subcapsular corpuscles in all animal groups. Despite their size variation, a striking transcortical uniformity was evident in the composition of glomeruli in each group with respect to the volume fractions and mean cell volume in each cell population, the volume and surface density of basement membrane, the volume and length density of capillary loops, the volume fraction of mesangial matrix, and the division of basement membrane into peripheral and axial portions.